1. Field of the Invention
The present invention relates to an image forming apparatus supervising system in which at least one copier or similar image forming apparatus and a central control system are interconnected by a data communication unit and a communication line.
2. Discussion of the Background
Typically, in an image forming apparatus supervising system, image forming apparatuses located at many and unspecified users' stations are connectable to a central control unit or host situated at a sales station or a service station by a data communication unit and a public network or similar communication network. The image forming apparatuses may be copiers subjected to remote diagnosis. The system implements efficient and immediate services by executing the following three kinds of controls (1)-(3):
(1) communication control from the central control unit to the image forming apparatuses;
(2) communication control from the image forming apparatuses to the central control unit or to the data communication unit; and
(3) individual control of the data control unit.
As for the term of use of the image forming apparatus, a distributor or a service company in charge of the apparatus often makes a contract with the user of the apparatus in terms of the number of sheets used to form images (block billing). In such a case, when the cumulative number of sheets used by the user reaches a billing number agreed upon at the time of contract, the central control unit situated at the distributor or the service company inhibits the apparatus from being operated any further, as needed, and urges the user to renew the contract. To inhibit or permit the further operation of the apparatus, the central control unit sends image formation control data representative of inhibition or permission to the apparatus. In response, the apparatus inhibits or allows the user to operate it.
However, the conventional system has the following problem left unsolved. Assume that the cumulative number of sheets used with the image forming apparatus reaches the billing number, and that the apparatus receives the control data representative of inhibition from the central control unit. Then, even when the apparatus is performing an image forming operation, it is forced to stop it and prevented from outputting a desired number of images.